It’s been a while since I’ve done a blog post purely dedicated to neuroscience, so this week I thought I’d write about a part of the brain that doesn’t always get much attention – the frontal lobe (also known as the frontal cortex). As the name suggests, the frontal lobe sits at the very front of your brain, just above your eyes. It is thought to be involved in ‘higher processing’ such as logic, or decision making, and it has therefore been hypothesised to be what distinguishes humans from other primates.
Perhaps the most famous study of the frontal lobe was conducted in 1848, following an accident to a man called Phineas Gage. Phineas was working as a railroad construction foreman when an explosion forced his tamping bar to fly upwards, through his cheek and into his brain. The force was so strong that the iron bar broke through the top of his skull and landed a few metres away. Amazingly, Gage survived and he lived for another 12 years after the accident. However his personality had changed completely – once polite and courteous he became rude and impulsive, and could never hold down another job.
Examinations of Gage’s skull show that the bar exited his head through the frontal region of his brain. Damasio et al (1994) were able to re-examine Gage’s brain using modern imaging techniques and modelled which brain areas were likely to have been affected. They found that the bar would have missed the language and motor areas, instead damaging an area known as the ventromedial frontal cortex. This area is thought to be responsible for regulating both emotions and behaviour, which explains the changes in Gage’s personality after his accident.
Accounts of Gage’s deficits after his injury suggest that he had problems with executive functioning after the accident. This term covers any kind of control we have over our behaviours, such as impulse control, problem solving and verbal fluency (e.g the Stroop test). Other studies exploring executive functions in people with frontal lobe lesions have also found that severity of a lesion is associated with worse scores on tasks designed to test these skills (e.g. Foong et al, 1997). However, it should be noted that the frontal lobe has high levels of connectivity with other areas of the brain, therefore it is unlikely that the frontal lobe alone is responsible for all aspects of executive function (Alvarez & Emory, 2006).
Interestingly, the frontal lobe has also been implicated in neurodevelopmental conditions like ADHD, as they also often feature impulsivity and impaired behaviour control. One neuroimaging study found that children with ADHD showed an inverse relationship between symptom severity and surface area of the frontal lobe (Dirlikov et al, 2015). However, more research is needed to explore the causal direction of this relationship.
Thanks for reading – see you next week for another post!
References:
Alvarez, J.A. and Emory, E., 2006. Executive function and the frontal lobes: a meta-analytic review. Neuropsychology review, 16(1), pp.17-42.
Damasio, H., Grabowski, T., Frank, R., Galaburda, A.M. and Damasio, A.R., 1994. The return of Phineas Gage: clues about the brain from the skull of a famous patient. Science, 264(5162), pp.1102-1105.
Dirlikov, B., Rosch, K.S., Crocetti, D., Denckla, M.B., Mahone, E.M. and Mostofsky, S.H., 2015. Distinct frontal lobe morphology in girls and boys with ADHD. Neuroimage: Clinical, 7, pp.222-229.
Foong, J., Rozewicz, L., Quaghebeur, G., Davie, C.A., Kartsounis, L.D., Thompson, A.J., Miller, D.H. and Ron, M.A., 1997. Executive function in multiple sclerosis. The role of frontal lobe pathology. Brain: a journal of neurology, 120(1), pp.15-26.
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